ChatGPT and Codex will share one token-based usage allowance on Plus, Pro and Business from December
OpenAI's updated help article says Codex, Work and other agentic ChatGPT use will draw from one combined allowance measured in tokens, so heavier models and longer tasks burn more of it, while Instant chat stays free of the meter. There's no exact December date or per-plan amount yet; combined remaining usage and reset times will show in Settings > Usage, with credits on sale when you run out.